In Japanese Patent Publication No. 2001-322540, a vehicle deceleration control device is proposed which generates deceleration in a vehicle by applying a supplemental braking force according to an operational state of an accelerator (for example, according to whether an accelerator pedal is released). When an output level of the accelerator decreases to a predetermined value, that is, the output level falls within a no-load operation range in which output power of an engine decreases to its minimum or the engine stops, the device generates the supplemental braking force by means of regenerative braking or the like, achieving a deceleration equivalent to that achieved by engine braking.
Although the achievement of the deceleration is described in the patent document cited above, no detailed disclosure is given regarding a method for determining the supplemental braking force to be applied to the vehicle.